Automatic telephone system



June 2, 1925.

LANE-r' o RELAYSA B C D E lF Ll NES I 1,540,419 W. T. POWELL AUTOMATIC TELEPHONE SYSTEM Filed Dec. 2B, 1920 2 Sheets-Sheet 1 FIG] INVENTOR VWNFRED T POWELL.

avldWw s: ess-s tra! um ATTORNEY June 2, 1925.'

w. 'r. PQwELL AUTOIATIG TELEPHONE SYSTEI Filed Dec. ze.` 1920 FIGB IS r i l [|33 y BIKER ATGR.

INVENTOR wmf-Ren T. Powsu. v

Patented June 2, 1925.

UNITED STATES PATENT i OFFICE@` WINFRED T. yIEOW'IEILL, OF ROCHESTER, NEW YORK, ASSGNOR- TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, OF

CORPORATION OF NEW YORK.

ROCHESTER, NEW YORK, A

AUTOMATIC TELEPHONE SYSTEM.

Application filed December 28, 192.0. Serial No. 433,677.

Be it known that l, lViNriinn T. POWELL, a citizen of the United States, residing at l'lochester, in the county of Monroe and rtritate of New York, have invented certain new and useful Improvements in Automatic Telephone Systems. of which the following is a full, clear, concise, and exact descrip-v tion.

This invention relates to telephone systenis and more particularly to telephone systems employing automatic switches for es tablishing connections between calling and called telephone lilies.

ln `former automatic telephone systems employing an individual trunk selectingswitch provided with independent operatinguneans, it was customary to piovide a socalled line relay for each line. vIn accordance with the present invention it is proposed to arrange the telephone lines iii groups and to provide a common group of relays, the total number of which relays is less than the number of lines, which group of relays performs the functions formei-ly performed by theline relay.` y

(lne feature of this invention therefore relates to novel means forcoiitrolling the individual trunk selector of a telephone line.

ii second feature of this invention resides in improved means for directively operating` numerical switches, While other features of the invention will appear from the detailed description and appended claims.

ln the drawings Fig; 1 diagrammatically i'i'ipresents the sub-station circuits of one telephone line of a group as well as the operating' circuits of the individualv trunk selector switch of this line, Vwhile at the lower portion there are represented three lgroups of relays which co-operate in the control of a pluralityof such line switches, ln Fig'. 2 there is represented the operating circuits of a connector switch as well as Vthe sub-station circuits of a second telephone line herein referred to as the called or wanted line.

In accordance with one embodiment of this invention the lines of the telephone system are arranged in groups of 100 lines cach and for the common use of each group of lines there are provided a group of relays arranged in three sub-groups for co cpeiatiiigg in the control of the motor mag.

nets of the line switches of the lines of the zgroup. Y

The trunk selector switch may be of thc type disclosed in the patent to Clement #1,107,153, `August 11, 1914, although it will be understood lthat variousforins oi rotary switches may be employed in which4 each set of normal contacts is followed `by one 4set of trunk contacts. `The connector switch may be of the form'disclosed in the patent to Keith, Erickson and Erickson #815,176, March 13, 1906, when modified to operate in a. so-called two wire telephone system.

'lhesmall numerals refer to the numerical designation of the lines of the group and thesenumbers as ywell as the letters associated with certain of saidV relays together with the code at the lower part .of Fig. 1', indicate which relays are related to the vari-` ous lines. f

Each sub-station is provided with a ydial sender of any preferred form which intei rugts the line circuit a numberof times in accordance with the desired setting' of the kdial sender.

The interruptions or impulses of each series are of equal duration, except the last which is much shorter than thev ture and back contact of the cut-off relay y.

105, over the upper side ofthe calling line, impulse springs 106, through the sub-'sta tion circuits, over the lower side of lthe calling line in series, inner upper armature and back contact of the cutoff relay, conductor 107, contacts 108 of relay' 112, conductor 109, winding of relay 110, secondary wind inte,` of the induction coil, to grount'ied `battery.' The primary winding of this lastl mentioned induction coil is connected toa source of dial tone current so that a tone is ktransmitted to the receiver of the calling subscriber until the circuits are in con dition `to receive the `first series of iin pulses fio'ni the subscribefs dial sender.

The relay is energized in the last described circuit and'completes an operating circuit from ground, its upper armature and front Contact, conductor' 111, winding of relay 112,'to grounded battery. Relay 112 closes the series of contacts shown at its right and lett-hand and thereby opens the contacts 103 to sever the operating circuit et the relay 110, but this relay because ot its slow releasing characteristics maintains the operating circuit for relay 112 for an appreciable interval. As soon as the relay 112 attracts its armatures, a circuit is closed ironi grounded battery, winding of the relay 113', contacts 114, conductor 107, over the two sides of the calling line in series to ground at the uppermost armatureand back contact or" relay 105. The relay 113 isthus operated to complete a locking circuit for the relay 112 from grounded battery, winding of' this relay, its innermost right-haiul front contact and armature, conductor 115, inner front .contact and armature of relay 113, conductor 116, winding koi" the impedance coil, to ground. lilith relays 113 and 112 operated ground potential is appliedl to the normal contacts 117 'from ground, uppermost front contact andarmature of relay 113, conductor 118,'to the contacts 117. This condition is effective to initiate the operation of the motormagnet 119 et the line switch which is actuated in a circuit traceable from ground-ed battery, Vwinding ofV this magnet, its back contact and armature, lower back Contact and armature of the cut ol" relay, brush 120, terminal 117, to ground, as previously described'. Under the control of this circuit the motor magnet 119 advances its brushes 120, 121, 122 and 123 into -engagement with the terminals ot trunk #1. n

Let it be assumed that thistrunk is busy, under Vwhich assumption its test terminal 124 would be characterized by ground potential and a circuit will thereby be completed tor operating the rmotor magnet 119 to radvance the brushes of the line switch into engagement with a second set ot home contacts 117 also` characterized by ground potential so that the motor magnet will advance the brushes of the line switch into engagement with thetern'iinals oi `a second trunk which is shown in 'full in these drawings. Y

Let it be assumed that this trunk is idle, a condition which is indicated by the ab# sence of potential on its test terminal 125. The cut-oil relay 105 will then be operated in a circuit completed from grounded battery, winding ot' the motor magnet and winding of the cut-oit' relay in series therewith, holding brush-121, conductor 126,-bacl Contact and armature ot the. release magnet 127, to ground. The cut-ott relay is energized in this circuit and, at its upper armatures and back contacts, it opens the circuits by which the group of relays was initially energized, while atthe front contacts of these armatures the calling line is extended to the line brushes 122 and 123. At the lowermost armature and front contact of cutoff relay, ground potential is applied to test brush and through its brush to the test terminal ot' the selected trunk to render yit non-selectable. It will also be understood that when the operating circuits of the groups of relays are open that the dial tone is disconnected from the calling line which indicates to the subscriber thereon that his line is connected to an idle numerical switch and that he may then operate his dial sender.

Then the calling line was connected to the line switch brushes122 and 123 by the operation of the cut-oft relay upon the seizure ot a selected trunk, the impulse relay 128 was energized in a circuit including both sides ot' the selected trunk and the call-y ing line in series. Relay 128 is energized in this circuit and at its lower armature and iront Contact completes a circuit for the slow releasingrelay 129 which controls the release or' the connector switch, as will be described.' The calling subscriber now 0perates his dial sender intermittently opening and closing the contacts 106 to transmit a series ot impulses corresponding to the tens digit of the wanted number. In response to this series ot impulses the impulse relay 128 vibrates its armatures and on its first deenergi-zation at its lower armature and back contact it closes a circuit trom ground, through the lower armature and front contact ofv relay 129, through the high resistance and low resistance windings of the ,change-overl relay 130 lin series, side switclrwiper 131, winding of the primary magnet 132, to grounded battery. Since it is assumed that this iirst impulse is relatively long,l the change-over relay 130 will .be energized in this circuit but the primary motor magnet will not operate in series with the high resistance winding of the changeover relay. The change-over relay 130 on energization short-circuits its high resistance winding by completing a circuit from ground, its lower armature and front contact, its upper low resistance winding, side switch wiper 131, winding oi the primary magnet 132, to grounded battery. This last named'magnet will now operate in series with the low resistance winding oi relay 130 and closes its armature and frontcontact. Betorethe impulse relay y128 is again attracted at the close ot the impulse just mentioned and with the armature and contact ot the yprimary motor magnet 132 closed, both windings of the changeover relay 130 are short-circuited by a circuit including conductor 133, front conta-ct andarmature et rela-y 129, back contact and armature of relay 128, to ground. Relay 13() therefore retracts its armatures. Shortly after this the impulse relay is operated and causes the primary motor magnet to release and advance the brushes 137, 138 and 139 onestep in the group selecting movement. This operation of relays 128 and 130 and magnet 32 is repeated for each impulse until the last `impulse of the series is transmitted.

This impulse is of short duration, as coni-` pared with those preceding it, so that the operation will now be as follows. The impulse relay 128 retracts its armatures and closes a circuit from ground, through its lower armature and back contact, armature and front contact of relay 129, both windings in series of relay 130. side switch wiper 131 in its first position, winding` of the primary motor magnet 132, to grounded battei-y. Relay 139 attracts its armatures and at. its lower armature short-circuits its high resistance winding and closes a circuit for energizing primary motor magnet 132.v However, before the primary motor magnet 132 operates, the impulse relay 128 attracts its armatures and the previously described short-circuit including conductor 133 is not completed, so that when the primary motor magnet 132 does operate it is locked energized through the side switch wiper 131k and the low resistance winding of relay 13()y to ground at its lower armature and front contact.` The escapeinagnet 134 is now energized over a circuit extending from grounded battery, resistance, winding of this magnet, sfide switch'wiper 135v in its first position, upper armatures and front contacts of relays 130 and 128, to ground. This magnet attracts its armatures and at its righthand armature closes a short-circuit about relay 130 which deenergizes and opens the circuit of the escape magnet thereby causingV the side switch wipers to be moved into their second position. lhen the escape magnet releases the primary motor magnet is deencrgized.

The subscriber now operates his dial switch to transmit impulses corresponding to the units digit of the wanted number. 1n response to thefiirst of these impulses the impulse relay 128 retracts its armatures andthe change-over relay 130 is now oper-` ated in a circuit closed from ground, lower armature and back contact of` impulse relay 128, armature and front Contact of relay 129, through both windings in series of relay 130, side switch wiper 131 in its second posi-tion, uppermost back contact and armature of test relay 140, winding of the secondary motor magnet 141, to grounded battery and, as described .in a previous instance, relay 130 is locked operated in series with the secondary motor magnet and short-circifis the high resist-,ance of that relay. The

Secondary motor magnet 141 is thereupon locked operated in a; circuit traceable from grounded battery, its winding, armature and front contact, conductor 133, front contact i motor magnet 141 deenergizes and advances the connector brushes over the terminals of the selected group of lines. In response to the next impulse of the series, impulse relay 128 retracts its armatures and again closes a circuit through both windings of relay 1.30 and magnet 141 .in series. Magnet 141 does not operate, but relay 139 d oes operate and short-circuits its high resistance winding to effect the operation of the motor magnet. This operation is continued until the last or short impulse of the series is received,` at the close of which the impulse relay `will attract its arn'iaturesbefore relay 130 is released and the escape magnet is operated in a circuit from grounded battery, resistance, winding of this magnet, side switch wiper 135` in its second position, front contacts and armatures of relays 130 and 128, to ground.` This magnet attracts its armatures and at its right-hand armature closes a short-circuit about relay 130, which releases to openthe original energizing circuit of the escape magnet. y

Let it be assumed that the called line is busy which condition is indicated by ground potential on the test terminal 142 of this line, so that the escape magnet will then be locked operated in a circuit` closed from grounded battery, resistance, its winding, armature and front contact, winding of test relay 140, its continuity spring and contact, conductor 143, side' switch wiper 144in its `second position, connector test brush 137,

test terminal 142, and a multiple terminal thereof through a test brush similar to 137 and a side switch wiper similar to 144v in its fourth position, to ground at the connector switch which has previously seized the Wanted line. The test relay is operated in this circuit and then locked operated in a circuit from ground, through the ott-noi` mal contacts 145, inner armature and continuity spring and winding of test relay 140, over the remainder of the circuit previously described as extending through the winding of escape magnet 134. lith lthe test relay 1.40 operated, a source of busy tone current BZ vis applied to the calling line through the lower armature and front contact of the Y test relay.

It will now be assumed that the wanted line is idle at the time when the test brush 13T enoae'ed the test terminal 142 of this Cfl circuit from grounded battery, resistance,

its winding, side switch wiper 185,- in its thirdposition, back contact and armature of release magnet 127, to ground. Also inv this position, an interrupted source of sig.- nalling current, herein designated generator is applied to the called line, through the winding of the trip magnet 146, side'switch wiper 147, connector brush 138, through the sub-station circuits and bell ot the called line,` over the upper side of thev line, connector-brush 139, side switch wiper 1&8 in its third position, to ground. The trip relay 1.46 is of the well known type which does not energize in series with the resistance ot called bell but, when the. called party responds, itdoes operate and closes a shortcircuit from ground, at its armature and front contact about the escape magnet which causes this magnet to release and move Ithe side switch wipers into their fourth or tall;n ing position. Y

At the termination of the call, the calling subscriber replaces his receiver on the switch -hook and thereby eilects the deenergiaation of the impulse relay 128 t-olopen the circuit of relay 129. which shortly afterwards deenergizes and closes the circuit for the rclease magnet 127 from grounded battery, winding of this magnet, oliv-normal contacts 149, back contacts and armatures oic relay 129 and the impulse relay 128, to ground, Relay 127 is energized to effect the release ofthe connector switch and restore its side switch wipers to normal position. The releasel magnet also attracts its armature to open the holding circuit including conductor 126 of the cut-ofi. relay 105 and this' relay deenergizes and retracts its armatures. Thereupon a circuit is-closed from ground at t-he armature and front contact of magnet 127, conductor 150, brush 120, lower armature and back contact of relay 105, armature,- back contact andy winding of the motor mag-A net 119, to grounded battery. Under the control of this circuit, the motor magnet 119 advances the brushes of the line switch to the next one of its normaly positions.

It will be understood that one or more selector switches may be interposed between the line switches and the connectors if the size of system requires such additions and other variations within the scope of the. claims may be made without department irom the spirit ot' the present invention.

that is claimed is:

l. In a telephone exchange system, a plurality of telephone lines divided into groups, va selecting' switch for the use ot' each telephone line, independent operating means for each switch, group of relays comino-n to each one ofsaid groups of lines and lessv in number than the number ot said telephone 'linesY for controlling the operating means of the selecting switch of the calling line, and -operating circuits for certain of said relaysincluding said telephone lines.

2'. In a telephone exchange system, a plurality of telephone lines arranged in groups, trunks for extending any of said lines in the direction of the called line, atrunk select-ing. switch for each teleph-one line operating to connect its l'ine with an idle trunk, individual operating means igor each trunk selecting' switch, a. plurality ot relays individual to each grou-p of lines arranged in subgroups, one subgroup of relays being common to certain of said lines and a second subgroup oi" relays being common to certain other lines, means for opera-ting afrelay in eachl subgroup on the initiationof a ca-ll, and means controlled ointly thereby for actuating the operating means of the .indivi-dual trunk selecting switch of the calling line. Y

3. In a. telephone exchange system, a plurality oftelepho-ne lines arranged in groups, a: plurality of trunks for interconnecting said telephone lines, a trunk selecting switch 'tor each line operating t0 select idle trunks, a group of line relays individual to eachv .groupof lines less Vin number than the number of said lines, said relays being arranged to be operated on the initiation of a. call,

and means controlled thereby for operating the trunk selecting switch of the calling line.

a. In a telephone exchange system, a plurality of telephone lines arrangedl in groups, a cut-olf relay for each telephone line, a f plurality of trunlrsy and numerical' switches for interconnecting" said telephone lines, a trunk selecting' switch for each line operat-v ing to select idle trunks, a group oit' line relays individual to each group of lines less in number than the number of said lines, said line relays being operated on the initiation of acall, means controlled thereby for operating the line switch of the callingV line to seize an idle trunk, and means responsive toI such seizure for operating the cut-otl relay and eli'ect the deen'ergi'zation of the operated line relays.

5. In a telephone exchange system, a. plurality of telephone lines arranged in groups, a plurality of trunks and numerical switches for interconnecting said telephone lines, a. trunk selecting switch for the use ot' each line operating to select idle trunks, a line relay comm-on to al plurality of lines in a group, a secondary line relay common to a second set of lines of a group, one ot' said telephone lines being common to both ot the last mentioned groups of telephone lines` a third relay common. to said firs-t group ot lines opera-ting' to disconnect said first relay and connect said second relay to the calling line, and means responsive to the operation of' said'T relays for effecting the operation of the trunk selectingswitch.

6. In a telephone system5 a; plurality of telephone lines, arranged in groups7 trunks und numerical switches for interconnecting said telephone lines7 a trunk selecting switch ilor the use of each telephone line operating to select idle trunks on the initiation of a call, a line relay common to a plurality of the lines of a group7 a seeond line relay eoinnion to a second set of lines of said group, one telephone line being eornnion to both groups of relays, a third lrelay common toA said first group of lines operating to disconneet said iirst relay and eonneet said seo .ond relay to said line on the initiation oi a call7 ope 'atingY means for said trunk selecting switch responsive to said relays for 15 causing said switch to seize an idle trunk, and a eut-ofi' relay operated on the seizure of an idle trunk to disable said operated relays.

In Witness whereof', I hereunto subscribe 20 my naine this 27 th day of Deeember A. D. 1920.

VINFRED T. POWELL. 

